Vascularized composite allograft rejection is delayed by infusion of IFN-γ-conditioned BMSCs through upregulating PD-L1.

Mesenchymal stromal cells (MSCs) have been applied in prevention from allograft rejection based on their immunomodulatory effects. However, conflicting results have been presented among recent studies, for which one possibility being acknowledged is that the exact effect is determined by the microenvironment when MSCs are applied in vivo. Using a hind limb composite tissue allograft model, we investigate the influence of IFN-γ-preconditioning on the immunomodulatory effects of MSCs and the subsequent allograft survival. Firstly, different doses of IFN-γ were respectively used to incubate with bone marrow-derived MSCs (BMSCs). We found that IFN-γ altered the expression of PD-L1, a major suppressor gene in the immune system during allograft rejection, in a strictly dose-dependent manner in BMSCs. Ten nanograms per milliliter IFN-γ-incubated BMSCs significantly stimulated PD-L1 expression and suppressed T cell proliferation and differentiation, while 50 ng/mL IFN-γ-incubated BMSCs sharply reduced PD-L1 expression. Moreover, we observed that, in contrast to the naive BMSC transplantation group, BMSCs pre-conditioned with 10 ng/mL IFN-γ (BMSCs-IFN-γ) significantly delayed the allograft rejection in vivo. In vitro mixed lymphocyte reaction (MLR) indicated that BMSCs-IFN-γ inhibited T lymphocyte proliferation and activation via PD-L1. Moreover, BMSCs-IFN-γ did not influence the proliferation and activation of T lymphocytes when PD-L1 protein was neutralized by the PD-L1 antibody. These data collectively reveal a role of recipient ongoing immune microenviroment in BMSC-based immunesuppressive therapy. Graphical abstract ᅟ.

[Method of Remote Sensing Identification for Mineral Types Based on Multiple Spectral Characteristic Parameters Matching].

The traditional mineral mapping methods with remote sensing data, based on spectral reflectance matching techniques, shows low accuracy, for obviously being affected by the image quality, atmospheric and other factors. A new mineral mapping method based on multiple types of spectral characteristic parameters is presented in this paper. Various spectral characteristic parameters are used together to enhanced the stability in the situation of atmosphere and environment background affecting. AVIRIS (Airborne Visible Infrared Imaging Spectrometer) data of Nevada Cuprite are selected to determine the mineral types with this method. Typical mineral spectral data are also obtained from USGS (United States Geological Survey) spectral library to calculate the spectral characteristic parameters. A mineral identification model based on multiple spectral characteristic parameters is built by analyzing the various characteristic parameters, and is applied in the mineral mapping experiment in Cuprite area. The mineral mapping result produced by Clark et al. in 1995 is used to evaluate the effect of this method, results show, that mineral mapping results with this method can obtain a high precision, the overall mineral identification accuracy is 78.96%.

[Effectiveness of posterior intercostal artery perforator flap in repair of donor defect after latissimus dorsi myocutaneous flap transfer].

Objective: To investigate the feasibility and effectiveness of the latissimus dorsi myocutaneous flap in repair of large complex tissue defects of limb and the relaying posterior intercostal artery perforator flap in repair of donor defect after latissimus dorsi myocutaneous flap transfer. Methods: Between January 2016 and May 2017, 9 patients with large complex tissue defects were treated. There were 8 males and 1 female with a median age of 33 years (range, 21-56 years). The injury caused by traffic accident in 8 cases, and the time from post-traumatic admission to flap repair was 1-3 weeks (mean, 13 days). The defect in 1 case was caused by the resection of medial vastus muscle fibrosarcoma. There were 5 cases of upper arm defects and 4 cases of thigh defects. The size of wounds ranged from 20 cm×12 cm to 36 cm×27 cm. There were biceps brachii defect in 2 cases, triceps brachii defect in 3 cases, biceps femoris defect in 2 cases, quadriceps femoris defect in 2 cases, humerus fracture in 2 cases, brachial artery injury in 2 cases, and arteria femoralis split defect combined with nervus peroneus communis and tibia nerve split defect in 1 case. The latissimus dorsi myocutaneous flaps were used to repair the wounds and reconstruct the muscle function. The size of the skin flaps ranged from 22 cm×13 cm to 39 cm×28 cm; the size of the muscle flaps ranged from 12 cm×3 cm to 18 cm×5 cm. The wounds were repaired with pedicle flaps and free flaps in upper limbs and lower limbs, respectively. The donor sites were repaired with posterior intercostal artery perforator flaps. The size of flaps ranged from 10 cm×5 cm to 17 cm×8 cm. The second donor sites were sutured directly. Results: All the flaps survived smoothly and the wounds and donor sites healed by first intention. All patients were followed up 10-19 months (mean, 13 months). At last follow-up, the flaps had good appearances and textures. The muscle strength recovered to grade 4 in 5 cases and to grade 3 in 4 cases. After latissimus dorsi myocutaneous flap transfer, the range of motion of shoulder joint was 40-90°, with an average of 70°. The two-point discrimination of latissimus dorsi myocutaneous flap was 9-15 mm (mean, 12.5 mm), and that of posterior intercostal artery perforator flap was 8-10 mm (mean, 9.2 mm). There were only residual linear scars at the second donor sites. Conclusion: The latissimus dorsi myocutaneous flap combined with posterior intercostal artery perforator flap for the large complex tissue defects and donor site can not only improve the appearance of donor and recipient sites, but also reconstruct muscle function, and reduce the incidence of donor complications.